An electrode system comprises electrode modules, flexible connectors, and sensors. Each electrode module defines a substantially central opening and has circuitry that includes an amplifier. A conductive ring is exposed in the opening of each electrode module. The flexible connectors include flexible circuitry coupled with the circuitry of the electrode modules. Each sensor includes an electrolytic hydrogel portion that is configured to contact a test subject and outwardly extending tabs that are in communication with the hydrogel portion. The tabs are configured to contact the conductive ring of an electrode module with the sensor is inserted in the opening of the electrode module. The system may thus sense evoked response potentials (ERPs) from the test subject through the electrolytic hydrogel portions, amplify those potentials, and communicate the amplified potentials through the circuitry of the flexible connectors. A control box may initiate ERP testing and store the test results.
